How are they making money?

Yesterday someone contacted me on upwork, offered a job about some mobile network testing. They sent me websites and all I had to do is find a pop up and to complete a mobile subscription offer. They sent me the cost for the subscription and also 4 dollars/hour. I'm curious how is that profitable for them?

They are getting paid more for each offer completed. Although they will probably get banned eventually.

Or they are just testing their system.